Audio production is a difficult career to train for as well as to break into, Rehnberg said, because it requires expertise in disparate fields: engineering, computers, other mechanical devices, and musical theory.

That's one reason that -- until The Beatles -- no major musician had experimented firsthand with producing. The band is so legendary in part because its members learned and mastered the technical aspects of recording.

"In the studio, on one side were the musicians," Rehnberg said. "On the other were actual scientists and engineers producing. [The Beatles] broke through the wall."

Now, many students at the lab want the same thing.

"It makes more sense to do it myself," said Kevin Gentz, a 103 student. "To see how it's done rather than others doing it for you."

Gentz, 23, plays guitar and plans on going into film audio. He previously took an audio-production class at the University of Iowa and job-shadowed at a recording studio, but he said The Sound Lab has been his best experience because of Rehnberg's emphasis on "hands-on" experiments; his other training was more "watch and learn."

Alyssa Morosko, 18, is a 101 student who said classes at The Sound Lab want to make her pick up her guitar again. She is also taking music-theory classes at Black Hawk College, but she said the classroom setting leaves something to the imagination, with less lab work. Two sessions into her class at The Sound Lab, Morosko has already learned how to record and manipulate the sound, something she had never done at Black Hawk or on her own.

That illustrates another barrier to entering the music-production field: the dearth of educational options. There are roughly 50 college-level programs in the United States, according to Education-Portal.com, but those can be expensive; an associate's degree program in audio production and engineering at the Institute for Production & Recording in Minneapolis runs $39,000.

And while music-business and music-theory classes are available at less-expensive schools such as Black Hawk College in Moline, there are no courses in audio production or engineering.

The Sound Lab can therefore serve as a survey of the field for people considering a more intensive program. Tuition for each class is $400, with a 10-percent discount for those who sign up for all three. The classes use the same textbook, an additional $40. (For more information, visit RiverMusicExperience.org/programs/soundlab.htm.)

Rehnberg said his students generally fall into two groups: 16- to 30-year-old men and women who want a career in audio production, and 45- to 55-year-old men who have been into audio for years as a hobby. Most are music lovers who want to produce or engineer their own music.

"A Fantastic Long-Term Investment"

Rehnberg said that as both an artist and a producer, he knows how hard it is to engineer his own recordings; it's tricky to separate and balance the emotional, artistic side of music with the technical production side.

But at the beginning of their careers, musicians almost always have to engineer themselves, he said. Knowing how to properly record your own music makes it easier to get gigs and be taken seriously by record labels.

"Recording and performing are kind of at odds mentally," Rehnberg wrote in an e-mail. "To engineer, you have to be very present and detail-oriented. To perform well, you need to be thoroughly warmed up, relaxed, and emotionally invested in the song, even emotionally transported. It helps to close your eyes. But of course, you can't monitor the input and output levels while being emotionally transported with your eyes closed."

Rehnberg has already made a mark on his students. Alumna Melanie Rivera took the classes last year in anticipation of a job at a recording studio in Liverpool, England. While that job didn't materialize, Rivera then founded a not-for-profit organization called Salsa Des Moines, which provides salsa classes to the community, entertainment at business meetings, and performances at festivals. She said the skills she acquired at The Sound Lab have helped in her new position.

"The Sound Lab is not just audio engineering; it's also the nitty gritty of recording," Rivera said. "I learned how to communicate with managers, the label ... the business side of organizing musical events."

Another alumnus, Dan Peart, recently competed in the Iowa Blues Challenge in the solo/duo division. He also recorded and released his first album, Truth Be Told.

Rehnberg summarized that knowing the technical and business aspects of the music industry is no longer optional: "There's almost no way to play music today without spending all your time around machines that need engineering, so learning to speak that language is a fantastic long-term investment for a musician to make."